The investors want to make money, and if they make a tool that is usable by more people than just experienced 3D artists who are tired of retopologizing their models, that both empowers many more people and potentially makes them more money.
Aside from that, it's impossible to tools replace artists. Did cameras replace painting? I'm sure they reduced the demand for paintings, but if you want to create art and paint is your chosen medium it has never been easier. If you want to create art and 3D models are your chosen medium, the existence of AI tools for 3D model generation from a prompt doesn't stop you. However, if you want to create a game and you need a 3D model of a rock or something, you're not trying to make "art" with that rock, you're trying to make a game and a 3D model is just something you need to do that.
Aside from that, it's impossible to tools replace artists. Did cameras replace painting? I'm sure they reduced the demand for paintings, but if you want to create art and paint is your chosen medium it has never been easier. If you want to create art and 3D models are your chosen medium, the existence of AI tools for 3D model generation from a prompt doesn't stop you. However, if you want to create a game and you need a 3D model of a rock or something, you're not trying to make "art" with that rock, you're trying to make a game and a 3D model is just something you need to do that.